1. Field of the Invention
The present invention relates to an electronic endoscope which has an endoscope channel and is provided with a solid state imaging device serving as imaging means, on the tip thereof.
2. Description of the Related Art
Medical endoscopes which allow a slender insertion portion to be inserted into body cavities to observe internal organs or the like, or performing various types of therapy by means of therapeutic tools inserted through a therapeutic tool channel, have been widely used. Also, in industrial fields, industrial endoscopes for observing or inspecting for damage or corrosion in boilers, gas turbine engines, chemical plants, and the like are also in widespread use.
In the case of inspecting the interior of a gas turbine engine, for example, using the industrial endoscope, the method which has been used is a follows: an assisting hook portion inserted through an endoscope channel provided to the endoscope beforehand is latched onto a movable turbine blade, and the tip of the endoscope is introduced to the interior of the engine. Then, the aforementioned turbine blade is slowly rotated, and inspection is made of whether or not there is any chipped or cracked portions or such on the fixed turbine blades and so forth, one blade at a time.
For example, Japanese Unexamined Patent Publication No. 60-233611 discloses observation fixing device for an endoscope consisting of a hook member provided with a key-like formation on the tip of a flexible shaft which can be masses through the interior of a channel of the endoscope, and tension fixing means for providing tension to the rear end of the aforementioned hook member protruding from the operating unit of the endoscope, thereby fixing the hook member, whereby the endoscope can be retained at a desired position in a sure manner and the desired portion can be thus observed.
Also, Japanese Unexamined Patent Publication No. 60-119747 discloses a forceps-pressing device consisting of detachable connecting means provided to the forceps introduction opening at the forceps insertion channel formed to the endoscope, and a sliding member and pressing means for pressing this sliding member, so as to fix the axial portion of the forceps projecting from the aforementioned introduction opening in a pressed state with force such as tension and the like, wherein the movable portion of the slide member and the pressing means are formed in a state parallel in the longitudinal direction. However, the imaging means for the endoscopes used with the aforementioned observation fixing device and forceps pressing means consists of a so-called fiber scope, using fiber optics.
In recent years, electronic endoscopes with solid state imaging devices provided on the tip thereof as imaging means have come into use, and these perform inspection within gas turbine engines by latching an assisting hook member into a turbine blade, in the same manner as with the aforementioned fiber scope.
However, as shown in FIG. 1, with industrial endoscopes having a solid imaging device such as a CCD provided on the tip to serve as an imaging device, the position of the light guide fiber and illumination window 102 serving as the illumination optical system for supplying illumination light to the observation window 101 and the CCD comprising the observation optical system for imaging the object, have been determined with higher priority. Accordingly, the position of the endoscope channel has been set as appropriate in the space left over after positioning the aforementioned observation window 101 and illumination window 102.
Accordingly, in the event that the form of the effective imaging plane 103 of the aforementioned CCD is rectangular, as shown by the double-broken line, there were cases in which the opening 104 of the endoscope channel was positioned at the short side of the CCD effective imaging plane 103.
In the event that a hook member is latched onto a turbine blade with an endoscope in which the opening 104 of the endoscope channel is positioned at the short side of the CCD effective imaging plane 103, and inspection is carried out in such a state, problems such as described below may occur.
The longitudinal dimensions and the width dimensions of the slender turbine blade which is the point of observation protruding from the engine shaft do not agree with the vertical and horizontal ratio of the aforementioned CCD effective imaging plane 103, and accordingly, the longitudinal direction of the slender turbine blade 106 is displayed in the direction following the short side of the monitor 105, as shown in FIG. 2. Accordingly, in the event that the tip 106a of the turbine blade 106 which is prone to chipping and cracking is displayed on the screen, part of the turbine blade 106 toward the engine shaft goes off the screen.
Accordingly, it is an object of the present invention to provide an electronic endoscope whereby a turbine blade can be displayed on the monitor screen in the longitudinal direction in its entirety from the base portion to the tip portion for endoscope inspection.
Stated simply, the electronic endoscope according to the present invention comprises: a solid state imaging device with a rectangular effective imaging plane built into the tip of the inserting portion; and an endoscope channel through which endoscope fixing pieces are inserted; wherein the opening of the endoscope channel is positioned to the long side of the effective imaging plane of the solid state imaging device at the aforementioned tip of the inserting portion.